–16–
C3716a–2–6/00 (rev. A) 01088
PRINTED IN U.S.A.
AD8361
REV. A
AD8361
VPOS
IREF
RFIN
PWDN
SREF
VRMS
FLTR
COMM
C1
0.1F
R1
75⍀
1
2
3
45
6
7
8
RFIN
C3
C4
0.1F
C2
100pF
IREF
PWDN
VPOS
SREF
VRMS
Figure 49. Characterization Board
AD8361
CHARACTERIZATION
BOARD
RFIN
PRUP +V
S
SREF IREF
VRMS
DC OUTPUT
RF SIGNAL
SMIQ038B
RF SOURCE
IEEE BUS
PC CONTROLLER
DC MATRIX / DC SUPPLIES / DMM
DC SOURCES
3dB
ATTENUATOR
Figure 50. Characterization Setup
8-Lead micro_SOIC Package
(RM-8)
0.009 (0.23)
0.005 (0.13)
0.028 (0.70)
0.016 (0.40)
6ⴗ
0ⴗ
0.037 (0.95)
0.030 (0.75)
85
4
1
0.122 (3.10)
0.114 (2.90)
PIN 1
0.0256 (0.65) BSC
0.122 (3.10)
0.114 (2.90)
0.193
(4.90)
BSC
SEATING
PLANE
0.006 (0.15)
0.002 (0.05)
0.016 (0.40)
0.010 (0.25)
0.043
(1.10)
MAX
6-Lead SOT-23-6L Package
(RT-6)
0.122 (3.10)
0.106 (2.70)
PIN 1
0.118 (3.00)
0.098 (2.50)
0.075 (1.90)
BSC
0.037 (0.95) BSC
1
3
4 5 6
2
0.071 (1.80)
0.059 (1.50)
0.009 (0.23)
0.003 (0.08)
0.022 (0.55)
0.014 (0.35)
10ⴗ
0ⴗ
0.020 (0.50)
0.010 (0.25)
0.006 (0.15)
0.000 (0.00)
0.051 (1.30)
0.035 (0.90)
SEATING
PLANE
0.057 (1.45)
0.035 (0.90)
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Problems caused by impedance mismatch may arise using the
evaluation board to examine the AD8361 performance. One
way to reduce these problems is to put a coaxial 3 dB attenuator
on the RFIN SMA connector. Mismatches at the source, cable,
and cable interconnection, as well as those occurring on the
evaluation board can cause these problems.
A simple (and common) example of such problem is triple travel
due to mismatch at both the source and the evaluation board.
Here the signal from the source reaches the evaluation board
and mismatch causes a reflection. When that reflection reaches
the source mismatch, it causes a new reflection, which travels
back to the evaluation board adding to the original signal inci-
dent at the board. The resultant voltage will vary with both
cable length and frequency dependent upon the relative phase of
the initial and reflected signals. Placing the 3 dB pad at the
input of the board improves the match at the board and thus
reduces the sensitivity to mismatches at the source. When such
precautions are taken, measurements will be less sensitive to
cable length and other fixturing issues. In an actual application
when the distance between AD8361 and source is short and well
defined, this 3 dB attenuator is not needed.
CHARACTERIZATION SETUPS
Equipment
The primary characterization setup is shown in Figure 50. The
signal source used was a Rohde & Schwarz SMIQ03B, version
3.90HX. The modulated waveforms used for IS95 reverse link,
IS95 nine active channels forward (Forward Link 18 setting),
W-CDMA 4- and 15-channel were generated using the default
settings coding and filtering. Signal levels were calibrated into a
50 Ω impedance.
Analysis
The conversion gain and output reference are derived using the
coefficients of a linear regression performed on data collected in
its central operating range (35 mV rms to 250 mV rms). This
range was chosen to avoid areas of operation where offset distorts
the linear response. Error is stated in two forms Error from Linear
Response to CW waveform and Output Delta from 25
°
C performance.
The Error from Linear Response to CW waveform is the difference
in output from the ideal output defined by the conversion gain
and output reference. This is a measure of both the linearity of
the device response to both CW and modulated waveforms. The
error in dB uses the conversion gain multiplied times the input
as its reference. Error from Linear Response to CW waveform is not a
measure of absolute accuracy, since it is calculated using the
gain and output reference of each device. But it does show the
linearity and effect of modulation on the device response.
Error from 25
°
C performance uses the performance of a given
device and waveform type as the reference; it is predomi-
nantly a measure of output variation with temperature.
